Navigation aid instrument for aircraft

ABSTRACT

Navigation aid instrument for an aircraft pilot including:
         a first display device (R 3 ) extending horizontally, wherein the center of the display device embodies the longitudinal axis (X) of the aircraft, a mobile marker can move on either side of the center of the first display device (R 3 ) indicating the aircraft flight direction relative to the ground, and the mobile marker is further away from the center of the display device (R 3 ) the further the aircraft drifts from the rectilinear flight path, and/or   two left (R 2 ) and right (R 1 ) display devices that extend vertically at a distance from each other and have the function of indicating the angle of inclination of the aircraft wings relative to the horizontal respectively on the left side or right side of the aircraft, wherein a mobile marker can move either along the left display device (R 2 ), or along the right display device (R 1 ) to indicate to the pilot which way his aeroplane is inclined and the value of the inclination is higher the further the mobile marker is away from the top of the left (R 2 ) or right (R 1 ) display device concerned.

This is a divisional application of U.S. patent application Ser. No.13/131,145, filed on May 25, 2011, which is the National PhaseApplication in the United States of International Patent ApplicationPCT/EP2009/064927 filed Nov. 10, 2009, which claims priority on EuropeanPatent Application No. 08169905.0, filed on Nov. 25, 2008. The entiredisclosures of the above patent applications are hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention concerns a navigation aid instrument for anaircraft. More specifically, the invention concerns an instrument forassisting the pilot of an aircraft during the approach and landingphases.

BACKGROUND OF THE INVENTION

The purpose of the project named Solar Impulse is to fly an aeroplanepowered solely by solar energy captured by a multitude of photoelectriccells distributed over the entire surface of the aircraft. To achievethis challenge, the apparatus must be very light and have a large wingspan, typically on the order of 61 meters, i.e. a wing span comparableto an Airbus A340 which weighs several hundred tonnes.

It goes without saying that there are enormous differences of controlbetween these two types of aircraft. Without going into detail, itshould be noted that the approach and landing phases are fundamentallydifferent for piloting these two types of aircraft. A large heavyaeroplane, which is heavily motorised, has considerably fewerconstraints during approach and the final landing phase. In fact, anycrosswind, even a relatively strong crosswind, does not cause any greatproblems of stability, and the angle of approach can easily be correctedsince the pilots have the ability to step on the gas and negotiate aslight turn. This being so, even if the technique and power of a largeairliner offer a relatively high safety margin, the final approach andlanding nonetheless remain complex flight phases requiring the fullattention of the pilots, who have to control a large number ofparameters within a short period of time.

The Solar Impulse pilot, while having to control the same parameters asin a conventional aircraft, will not have a power reserve enabling himto easily correct the path, particularly in the last hectometerspreceding touchdown on the runway. Because of the extremely reducedweight and large wing span of this aircraft, it will be very sensitiveto side winds and will only have a very limited possibility formanoeuvre during the final approach. It was therefore necessary to finda way of giving the pilot information relating to the angle of approachand the inclination of the wings of his aircraft.

As regards the angle of approach, it can be said that when an aeroplanewishes to land, it is normally directed towards the threshold of therunway in a straight line. However, it is of course sensitive tocrosswinds which may cause it to deviate from its path. This is how, inthe event of crosswind, the pilot, if he looks straight ahead, willnotice that the runway is slightly to the left, or to the right relativeto the nose of the aircraft. The power of the engines of a conventionalaircraft will enable the pilot to correct the angle between therectilinear path and the runway threshold.

For a Solar Impulse type aircraft, the pilot has no power reserve and hemust therefore prepare the approach either by adhering as closely aspossible to the straight line, or by anticipating the drift of theaircraft due to the crosswind as early as possible. To do so, the pilot,who is already extremely occupied with other approach manoeuvres, musteasily be able to see the correction that has to be made to his path inorder to approach the runway threshold properly. Moreover, he must alsobe able to know whether the wing is perfectly horizontal, because, as itis very large, it is liable to touch the runway on landing if it isinclining too far on one side or the other. It should be realised thatwith a wing span of 61 meters, it is practically impossible for thepilot to visualise an inclination of the wings of one or two metersrelative to the perfect horizontal.

SUMMARY OF THE INVENTION

It is an object of the present invention to answer the aforementionedrequirements by providing a navigation aid instrument which allows anaircraft pilot to assess, in a simple stroke, the angle of inclinationof the wings of his aircraft and the drift relative to the rectilineardirection which will bring him to the runway threshold.

The invention therefore concerns a navigation aid instrument for anaircraft pilot, characterized in that it includes a horizontallyextending display device, wherein the centre of said display deviceembodies the longitudinal axis of the aircraft, a mobile marker that canmove on either side of the centre of the display device indicates theflight direction of the aircraft relative to the ground, i.e. the angleformed by the longitudinal axis of said aircraft and the horizontalcomponent of the velocity vector of said aircraft, wherein the angle ispositive on the right side of the longitudinal axis of the aircraft,and, the more the aircraft drifts from its rectilinear flight path, thefurther the mobile marker moves away from the centre of the displaydevice.

According to a complementary feature of the invention, the mobile markermoves on a scale comprised between −15° and +15°.

According to a particular embodiment of the invention, the displaydevice is achieved using a row of light emitting diodes, wherein thecentre of said row of diodes embodies the longitudinal axis of theaircraft, and one diode in the row of diodes lights up to the right orleft of the central diode to indicate to the pilot the flight directionof the aircraft relative to the ground. The display resolution providedby the row of diodes will be at least ±1° and preferably ±0.4°. It willbe clear that this resolution is not absolute. It depends upon thedistance between the pilot's head and the instrument. Thus, it is evenpossible for the resolution to be different for different pilots. Onediode in the row of diodes will indicate a drift of one degree betweenthe longitudinal axis of the aircraft and the horizontal component ofthe velocity vector of said aircraft.

According to another embodiment of the invention, the aircraftnavigation aid according to the invention includes two, left and right,vertically extending display devices at a distance from each other andhaving the function of indicating the angle of inclination of theaircraft wings relative to the horizontal respectively on the left sideor right side of said aircraft, wherein the angle of inclination ispositive when the aircraft wings are inclined to the right side, and amobile marker can move either along the left display device, or alongthe right display device to indicate to the pilot which way hisaeroplane is inclined and the value of the inclination.

According to a particular embodiment of the invention, the two, left andright display devices are each made using a row of light emittingdiodes, wherein one diode in one of the left or right diode rows lightsup to indicate the side on which the aeroplane is inclined and by howmany degrees the wings are inclined relative to the horizontal. Thedisplay resolution provided by the two rows of diodes will preferably be±1°, with one diode of either of the two rows of diodes indicating a onedegree inclination of the aircraft. Advantageously, the two verticalleft and right display devices supply an indication of the inclinationof the wings comprised between 0° and 5°.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will appear moreclearly from the following detailed description of an example embodimentof the navigation aid instrument according to the invention, thisexample being given solely by way of non-limiting illustration withreference to the annexed drawing, in which:

FIG. 1 is a perspective view of an aircraft fitted with the navigationaid instrument according to the invention;

FIG. 2 is a schematic view of the navigation aid instrument according tothe invention including a horizontal row of light emitting diodes forindicating a drift between the longitudinal axis of the aircraft and thehorizontal component of the velocity vector of said aircraft and twovertical rows of light emitting diodes for indicating the inclination ofthe aircraft wings relative to the horizontal on the left side or rightside of said aircraft, and

FIG. 3 is a similar view to that of FIG. 2, where the light emittingdiodes are replaced by liquid crystal display cells.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Solar Impulse pilot will have to keep the angle of inclination ofthe wings close to zero when flying level and very low (typically lessthan 5°) in the turns. Moreover, the angle formed by the aeroplane'sflight direction relative to the ground must be very preciselycontrolled. It is sometimes difficult to determine which direction theaeroplane is travelling in, which significantly increases the workloadof the pilot, particular during the approach phases. The low speed ofthe aircraft and the high side slip angle even with a moderate crosswindadd additional difficulty. A conventional instrument panel does notprovide precise information concerning the angle of inclination andvelocity vector direction for properly carrying out all of the flightphases. It has thus been deemed necessary to provide an instrumentproviding a display of these parameters that is easy to read, inparticular a precise indication of the angle of inclination in proximityto zero degrees and the flight direction relative to the ground, toassist the pilot during the final approach to landing.

The angle of inclination will be designated (Φ), i.e. the angle betweenthe transverse axis (Y) of aeroplane 1 (FIG. 1) and the horizontalplane. Φ is positive when the aircraft leans to the right. Moreover, theside slip angle will be designated (β), in other words the angle betweenthe longitudinal axis (X) of the aircraft and the horizontal componentof the air velocity vector. β is positive on the right side oflongitudinal axis X of the aircraft. Finally, the angle of drift will bedesignated (Ω), i.e. the angle between the horizontal component of theair velocity vector and the runway on the ground. Ω is positive to theright of the air velocity vector.

The main function of the aircraft navigation aid instrument according tothe invention is to provide a clear view of the angle of inclination Φof the aircraft with a precision of one degree for the first fivepositive or negative degrees of inclination. Beyond 5 degrees, the angleof inclination no longer needs to be indicated by the instrumentaccording to the invention, given that it can be assessed withsufficient precision by the instruments of a conventional instrumentpanel. Another function of the aircraft navigation aid instrumentaccording to the invention is that it allows the pilot to monitor andcorrect the flight direction relative to the ground, or in other wordsthe angle resulting from the sum of the side slip angle β and the driftangle Ω. Only the horizontal component of the velocity vector will bedisplayed, which will allow the pilot to be informed as to his flightdirection in terms of azimuth but not elevation. Finally, the instrumentaccording to the invention must be able to warn the pilot when the angleof inclination Φ reaches 6° (this value can be adjusted as required).This alarm must be both visual and sensory. The alarm will therefore beproduced in the vibrating sleeves of the pilot's flight suit. In otherwords, if the wing leans too far to the right, the right sleeve willvibrate, indicating to the pilot that he must correct the inclination ofthe left wing.

The pilot must be able to be informed of all the aforementionedparameters (angle of inclination and flight direction) clearly andwithout any possible source of error, both day and night. This objectivecan be achieved with suitable sizing and a careful choice of colours andsymbols.

The navigation aid instrument according to the invention is based onrows of coloured light emitting diodes arranged on the instrument panel.FIG. 2 below illustrates the desired arrangement.

The rows of light emitting diodes indicating the angle of inclinationand flight direction are arranged on the top part of instrument panel 2.Diodes D2 dedicated to indicating the angle of inclination are separatedby a space of 5 mm. There are five in each row, namely one diode perdegree of inclination.

A precise indication of the angle of inclination is provided by twovertical rows of light emitting diodes, a right row R1 and left row R2.One or several diodes, namely one diode per degree of inclination, whichplay the part of a mobile marker by producing a bright blue light, willlight up in succession to indicate an inclination of the wing to theleft side or right side under the horizon. Thus, if the aeroplane isflying perfectly horizontally, none of diodes D2 will light up. However,if the right wing of the aircraft is inclined by 3°, three diodes D2 ofright row R1 will light up in succession and remain lit up until thepilot has re-established the attitude of the aeroplane by correcting theinclination in the opposite direction. The angle of inclination isdisplayed on a range of ±5°. The number of diodes D2 lit up from the topof a row R1, R2 indicates the value of the angle in degrees up to 5°. Inthe example shown in the drawing, the first diode starting from the topof row R2 of diodes D2 is lit up, indicating an inclination of 1° of theaircraft wings on the left side.

If the angle of inclination reaches 6° or more (adjustable value), theentire row of five diodes on the right or left side concerned will startto flash at a frequency of 2 Hz and the signal intended to produce thealarm in the vibrating sleeve of the pilot's flight suit will begenerated.

Diodes D1 for supplying a precise flight direction indication arearranged in a horizontal row R3 arranged above the two rows R1 and R2 ofdiodes D2. The flight direction reading precision must not be less than1°. A diode D1 is therefore provided for each degree of drift of theaircraft flight direction relative to the ground. The horizontal row R3of diodes D1 will have a pale blue background colour from which a diodeD1, playing the part of mobile marker, will stand out by indicating inbright green the direction of the horizontal component of the velocityvector relative to the ground. For indication of the velocity vectordirection, the measuring range will be ±15° given that the pilot's eyesare around 70 cm from the instrument panel 2 and that the top right partof the panel measures 35 cm. For flight directions greater than 15°relative to the longitudinal axis of the aircraft, the bright greendiode will remain lit up permanently at the end of row R3 of diodes D1on the appropriate side. The diode marking the zero in row R3 of diodesD1 and the diodes marking −10° and +10° in the same row R3 of diodes D1could be staggered (see FIG. 2) for example downwards to provide visualmarkings to the pilot. In the example shown in the drawing, it is seenthat the third diode to the left of the centre of row R3 of diodes D1 islit up, indicating therefore a drift of −3° of the longitudinal axis Xof the aircraft relative to the rectilinear flight direction.

In flight, all of the diodes will be dark, with the exception of:

-   -   horizontal row R3 of diodes D1 which will always be illuminated        in a pale blue colour, thus providing the pilot with a lateral        reference axis    -   one diode D1 of horizontal diode row R3 will indicate in bright        green the direction of flight (if the aircraft is flying in a        perfectly rectilinear manner only diode D1 at the centre of row        R3 will be lit up);    -   the two vertical rows R1 and R2 of diodes D2 will indicate in a        bright blue colour the value of the the angle of inclination up        to 5°. The five diodes D2 of a given row will flash in blue for        an angle of inclination equal to or higher than 6°.

Two dimmer switches are provided, one for adjusting the pale bluebackground of the horizontal row R3 of diodes D1, and the other forregulating the brightness of the brightest green velocity vectorindicator and the brightest blue angle of inclination indicator.

It will be clear that the navigation aid devices according to theinvention, based on the use of rows of light emitting diodes could bereplaced, for example, by liquid crystal display devices. Thus a liquidcrystal display 3 of elongated rectilinear shape could be arrangedhorizontally indicating the aircraft flight direction relative to theground, i.e. the angle formed by the longitudinal axis of said aircraftand the horizontal component of the velocity vector of the aircraft. Theliquid crystal display could be backlit and light coloured when theaeroplane is flying in a straight line. The liquid crystal display couldthen gradually get darker from the centre towards the left or rightaccording to whether the aircraft is moving away from the rectilinearpath to the left or right. Likewise, two display screens of elongatedrectilinear shape 4 and 5 could be arranged vertically indicating theangle of inclination of the aircraft wings relative to the horizontal.These screens could be backlit and light coloured when the aeroplane isflying on the horizontal. One of the two screens would then graduallyget darker from the top according to whether the aircraft wingsinclining to the right or the left.

The invention claimed is:
 1. A navigation aid instrument for an aircraftpilot comprising: a left display device and a right display device,wherein the left and right display devices indicate a left-right angleof inclination of both aircraft wings relative to a horizontal, whereinthe angle of inclination indicates respectively whether the wings areinclined on a left side or a right side of the aircraft, wherein theangle of inclination is positive when the aircraft wings are inclined onthe right side, wherein a mobile marker is movable only along the leftdisplay device or only along the right display device to indicate to thepilot the side the aeroplane that is inclined, wherein the left and theright display devices extend vertically on opposite sides relative to aninstrument on the instrument panel of the aircraft and at a distancefrom each other, wherein the larger the angle inclination is, thefurther the mobile marker is away from the top of the left or the rightdisplay device concerned, and wherein the resolution of the angle to bedisplayed by the two display devices is ±1° relative to the positionthat the aircraft wings extend horizontally.
 2. Navigation aidinstrument according to claim 1, wherein the left and right displaydevices supply an indication as to the inclination of the aircraftrelative to the horizontal comprised between 0° and 5°.
 3. Navigationaid instrument according to claim 1, wherein the two left and rightdisplay devices each include a row of light emitting diodes, wherein oneor several diodes in one or other of the right or left diode rows lightsup to provide the pilot with an indication of the inclination of theaircraft wings relative to the horizontal, the diodes light up one afterthe other from the top to the bottom of the row concerned.
 4. Navigationaid instrument according to claim 2, wherein the two left and rightdisplay devices each include a row of light emitting diodes, wherein oneor several diodes in one or other of the right or left diode rows lightsup to provide the pilot with an indication of the inclination of theaircraft wings relative to the horizontal, the diodes light up one afterthe other from the top to the bottom of the row concerned.
 5. Navigationaid instrument according to claim 3, wherein one diode in the diode rowindicates a difference of one degree between the transverse axis of theaircraft and the horizontal.
 6. Navigation aid instrument according toclaim 4, wherein one diode in the diode row indicates a difference ofone degree between the transverse axis of the aircraft and thehorizontal.
 7. Navigation aid instrument according to claim 1, whereineach of the left and right display devices is formed by a liquid crystaldisplay cell that extends vertically and that is in a light colouredstate when the aircraft is flying horizontally, wherein the left orright display device concerned gradually gets darker from the top to thebottom as the aircraft wing inclines under the horizon on thecorresponding side.
 8. Navigation aid instrument according to claim 1,wherein it generates an alarm in the pilot's flight suit when theinclination of the aircraft wing relative to the horizontal reaches apredetermined value.
 9. Navigation aid instrument according to claim 8,wherein the alarm is triggered when the inclination of the wing isgreater than or equal to 6°.
 10. Navigation aid instrument for anaircraft pilot, including two left and right display devices accordingto claim 1.